In order to protect human beings and animals from diseases and annoying effects of nuisance insects, as for example bites or stings, a number of solutions have been developed throughout the years. One of the mostly known solutions is covering a certain area, for example the bed of a human being, by a mosquito net that prevents the person under the mosquito net from being bit by insects as mosquitoes or flies.
In U.S. Pat. No. 5,048,551, a special development within the field of protection of human beings against flying insects is disclosed, namely a floating insect screen for a user in a swimming pool. This insect screen has a base member connected to a number of upright members between which a mesh materials is attached preventing insects to reach the person under the floating insect screen.
In order to increase the efficiency of mosquito nets, it is known to impregnate the mesh material of the net with an insect repellent or even with insecticides to kill insects that touch the net structure. For people wearing clothes, also garments may be impregnated with insect repellents and/or insecticides as a protective agent.
Different agents to be used as insect repellents and insecticides are disclosed in international patent applications WO 98/18998 and WO 01/37662 and in European patent application EP 382 382 and references therein. Also disclosed in these patent applications and in references therein are water repellent agents, for example silicon oil or wax, to prevent washing off the insect repellent or insecticide and also UV-radiation protecting agents that prevent the insect repellent or insecticide from being decomposed due to UV-radiation.
Another attempt to reduce nuisance by insects is through killing of insects by air spraying, for example in insect breeding places. Air spraying of insecticides is furthermore used to reduce the effect of insects on agricultural fields.
Especially in tropical countries, a large number of insects, typically flying insects, causes substantial problems as vectors and transmitters of infectious diseases, as for example trypanosomiasis, affecting human beings and animals, why tremendous efforts have been concentrated in controlling these insects. However, especially for poorer countries, the expenses related to these efforts, especially the high price of insecticides, has a non-negligible influence on the economy of these countries. Using large amounts of insecticides by spraying over, for example agricultural fields, also may cause environmental problems. Further, it limits the possibilities for these countries to export their crops, since pesticide residues may be left on the crop and be detected by the authorities in importing countries. The European or North American farmer is confronted with the same problem of protecting versus retention of crop after spraying. When applying pesticides directly on crops, retention times must be respected, but this may be hard for farmers, especially when harvesting sorts of fruits and vegetables that are harvested over a period. By respecting retention time for ripening fruits, younger fruits risk to be damaged to a point that they can never be sold. In addition it implies the risk of resistance of the insects against the insecticide.
Regarding the fact that a large number of flying insects are a nuisance to human beings and animals either directly through insect attack or indirectly through agricultural effects caused by insects, it would be desirable to find a solution how to limit the negative influence of insects on daily life. Particularly, it would be desirable to find a solution to repel or kill insects that attempt to reach humans, animals or agricultural plants. Especially, it is interesting to prevent a contact between the insect and the host (human, animal or plant), since even a short contact time may be enough for the insect to damage the host. Insects carrying diseases may need only a few seconds after landing to damage the host. Treatment of walls in a house may thus well kill the mosquitoes, but the mosquitoes mostly rest on the walls after biting and have as such already transferred a disease. Aphids transferring opportunistic virus probe plants at landing and in this way transfer the virus. Both group of insects will land on a net that protects the host and even they may physically penetrate, they will already have received a dosage of insecticide that may disturb their behaviour and thus decrease their chance to transfer a disease.